The platypus, classified as a mammal because it produces milk and is covered in a coat of fur, also possesses features of reptiles, birds and their common ancestors, along with some curious attributes of its own. One of only two mammals that lays eggs, the platypus also sports a duck-like bill that holds a sophisticated electrosensory system used to forage for food underwater. Males possess hind leg spurs that can deliver pain-inducing venom to its foes competing for a mate or territory during the breeding season.

“The fascinating mix of features in the platypus genome provides many clues to the function and evolution of all mammalian genomes,” says Richard K. Wilson, Ph.D., director of the The Genome Center at Washington University and the paper’s senior author. “By comparing the platypus genome to other mammalian genomes, we’ll be able to study genes that have been conserved throughout evolution.”

The platypus represents the earliest offshoot of the mammalian lineage some 166 million years ago from primitive ancestors that had features of both mammals and reptiles. “What is unique about the platypus is that it has retained a large overlap between two very different classifications, while later mammals lost the features of reptiles,” says Wes Warren, Ph.D., an assistant professor of genetics, who led the project.

Comparison of the platypus genome with the DNA of humans and other mammals, which diverged later, and the genomes of birds, whose ancestors branched off an estimated 315 million years ago, can help scientists fill gaps in their understanding of mammalian evolution. The comparison also will allow scientists to date the emergence of genes and traits specific to mammals.

The Nature paper analyzes the genome sequence of a female platypus named Glennie from New South Wales, Australia. The project was largely funded by the National Human Genome Research Institute, part of the National Institutes of Health, and includes scientists from the United States, Australia, England, Germany, Israel, Japan, New Zealand and Spain.

“At first glance, the platypus appears as if it was the result of an evolutionary accident,” says Francis S. Collins, M.D., Ph.D., director of NHGRI. “But as weird as this animal looks, its genome sequence is priceless for understanding how mammalian biological processes evolved.”

“While we’ve always been able to compare and consider all of these creatures on the basis of their physical characteristics, internal anatomy and behavior, it’s truly amazing to be able to compare their genetic blueprints and begin to get a close-up look at how evolution brings about change,” Wilson says.

As part of their analysis, the researchers compared the platypus genome with genomes of the human, mouse, dog, opossum and chicken. They found that the platypus shares 82 percent of its genes with these animals. The chicken genome was chosen because it represents a group of egg-laying animals, including extinct reptiles, which passed on much of their DNA to the platypus and other mammals over the course of evolution.

The researchers also found genes that support egg laying - a feature of reptiles - as well as lactation - a characteristic of all mammals. Interestingly, the platypus lack nipples, so its young nurse through the abdominal skin.

The researchers also attempted to determine which characteristics of the platypus were linked to reptiles at the DNA level. When they analyzed the genetic sequences responsible for venom production in the male platypus, they found it arose from duplications in a group of genes that evolved from ancestral reptile genomes. Amazingly, duplications in the same genes appear to have evolved independently in venomous reptiles.

The platypus swims with its eyes, ears and nostrils closed, relying on electrosensory receptors in its bill to detect faint electric fields emitted by underwater prey. Surprisingly, the researchers found the genome contains an expansion of genes that code for a particular type of odor receptor. “We were expecting very few of these odor receptor genes because the animals spend the majority of their life in the water,” Warren says.

Similar genes are found in animals that rely on a sense of smell, such as rodents and dogs, and the scientists suspect that their addition in the platypus allows the animals to detect odors while foraging underwater.

At roughly 2.2 billion base pairs, the platypus genome is about two-thirds the size of the human genome and contains about 18,500 genes, similar to other vertebrates. The animal has 52 chromosomes, including an unusual number of sex chromosomes: 10. The platypus X chromosome bears resemblance to the sex chromosome of a bird, known as Z.

Sequencing and assembling the platypus genome proved far more daunting than sequencing any other mammalian genome to date. About 50 percent of the genome is composed of repetitive elements of DNA, which makes it a challenge to assemble properly.

The platypus genome sequence, along with those for other organisms, such as the mouse, dog, cow, and many other animals can be accessed at GenBank (www.ncbi.nih.gov/Genbank) at NIH’s National Center for Biotechnology Information.

[Caroline Arbanas @ Washington University School of Medicine]

The Socratic dialogue is a particular way of developing children’s, as well as adults’, thinking skills through cooperative dialogue where significant human ideas and values are discussed. By participating in Socratic seminars regularly every other week, preschool children and older students develop their thinking skills. The seminars address literature and art work, with questions such as these: is Pippi Longstocking a good friend, is Jack stupid or smart when he sells his mother’s cow for some beans, or are we born good or evil? In the beginning the students have difficulty expressing their thoughts, but with time their ability to express themselves and to examine ideas critically and logically develops.

The study included seven groups of children, five to sixteen years old. The groups were filmed during three years of philosophizing in the classroom and the films were analyzed. The interaction in the classroom was positively influenced, according to Ann S Pihlgren. The teacher dominated less, more students spoke and the students gradually took over the responsibilities of the teacher to promote exploration in the dialogue. The ability to use the Socratic seminar is learned by students and teachers through practice and by testing the rules of the seminar. The students construct a supportive group culture through their silent interaction, where gestures, glances, and body language are used to show not only support or sympathy for each other, but also cooperation with each other when someone attempts to disturb or to provoke the dialogue. The teacher role changes to one of support, ensuring that the analysis is fruitful and that the dialogue is respectful.

Socratic methods have developed independently in various countries. They all describe a set of methodological steps to attain similar objectives. An opening question is answered by all participants and followed by cooperative, critical analysis. Finally, the new ideas are connected to the everyday life experience of the participants.

It seems as if this ritualized structure and the nurturing culture of the seminar provide a safe circle, helping the participants to try new, bold ideas that they might otherwise not have tested, Ann S. Pihlgren says. By cooperating when examining the ideas they also seem to learn a way to address problems on their own without teacher intervention.

To work with methods connected to the ancient philosopher Socrates may seem out-of-date in a modern school, but that is absolutely not the case, Ann S. Pihlgren states.

The Socratic seminars have been seen as a complement to traditional classroom teaching for hundreds of years. But it is not easy to learn how to stage them to get positive effects. It is especially hard for teachers, who often fall back to their traditional, controlling “teacher” roles. The dissertation offers excellent tools for teachers who want to develop students’ thinking and to foster cooperative group dialogue.

The name of the dissertation: Socrates in the Classroom. Rationales and Effects of Philosophizing with Children. The dissertation can be downloaded as a pdf here.

[Jonas Ablad @ Swedish Research Council]

Developed by the creative team that brings you Make — the groundbreaking magazine devoted entirely to DIY technology — and authored by Matthew Weaver and Duane Wessels, this latest title presents clear, easy-to-follow instructions for making your own easily customizable geeky devices by learning how to build and customize small form factor PCs from scratch.

“We want to show you how they work, how they look (inside and outside), and how you can use them,” write Weaver and Wessels. “We’ve written this book for people who like to tinker with both computer hardware and software.”

The book is also written for those of us who think smaller is better when it comes to computers. As Wessels elaborates, “Nobody wants a large, noisy, 200-Watt computer sitting on their entertainment center. And why use a full-size computer for your network firewall when a much smaller computer gets the job done while using only 1/10th the power? We want people to see how easy and fun it is to turn a small form factor computer into something that you can use in your home or workplace.”

The projects devised by Weaver and Wessels include all the necessary details for building eight different systems, from the shoebox-sized Shuttle system down to the stick-of-gum sized gumstix.

Thorough illustrations and step-by-step instructions make creating these projects easy:

• Digital Jukebox. Play your music collection with this Mini-ITX system that will fit anywhere
• Digital Video Recorder. Record and watch live television using a Shuttle ST62k-based system
• Network Appliances. Create and configure your own router and network monitor using embedded computers from Soekris
• Wi-Fi Extender. Extend the range of your Wi-Fi network with the Access Cube
• Portable Firewall. Protect your computer from unknown networks with a USB-powered firewall based on the OpenBlockS
• Handheld Wi-Fi Console. Turn the ZipIt Wireless Messenger into a go-anywhere, text-only, wireless handheld
• Tiny Bluetooth gizmo. Use the Bluetooth-powered gumstix computer to talk to cell phones, PDAs, and more

Shoebox sized and smaller, small form factor PCs can pack as much computing muscle as everything from a PDA to a full-sized desktop computer. Even better, they consume less power, have few or no moving parts, and are very quiet. Whether you plan to use one as a standalone PC or want to embed it in your next hacking project, this new up-to-the-minute resource from Make Projects is a must.